Food warmer



April 22,1941. M, P, DUKE 2,239,500

Foon WARMER Filed Deo. 15, 1939 2 sheets-sheet 1 FIG. 2.

M. P. DUKE FooD WARMER Filed Dec. 13, 19:59

April 22, 1941.

2 Sheets-Sheet 2 Patented Apr. 22, 1941 UNiT-En STATES PATENT OFFICE yFOOD WARMER Marsh P. Duke, University City, Mo., assignorto 'DukeManufacturing Company, St. Louis, Mo.,

a corporation of Missouri Application December 13, 1939, VSerial No.308,937

' s claims. (o1. 12e-261') This'inventlon relates to food warmers,'andwith regard to certain more specic features, to foodwarming tables.

The invention is a continuation-ln-part of the invention specified in myapplication Serial No. Y

254,393, filed February 3, 1939, eventuated as Patent No. 2,231,615,dated February 11, 1941, for Food Warmer.v

Among the several objects of the present invention may be noted theprovision of a food- Warmer which is capable of warming a substantialvariety of foods, each of which may require to be maintained at asubstantially different temperature; the provision of a food warmer ofthe class described by means of which the heating of dilerent foodsthereon nbe independently or simultaneously accelerated and which ingeneral reduces the time and cost of heating; the provision of`apparatus of the class described which in refrigerated restaurants andthe li/e reduces the heat/which must be absorbed by therefrigeratingfequipment; and the provision `of apparatus of this classwhich operates dry without the production of unnecessary steam and whichis simple in construction and operation. Other objects will be in partobvious and in part pointed out hereinafter.

The invention accordingly comprises the elementsand combinations ofelements, features of construction, and arrangements of parts which Fig.4 is a vertical section taken onl line #-4 of Figrl; and,

Fig. 5 is a, vertical section taken-on line 5-5 of Fig. 4.

Similar reference characters indicate corresponding parts throughout theseveral views ofA l Since many of the fer to closely adjacent sheetsoimetal, such portions have been exaggeratedA in their relativespacings, `inforder to` clarify the descriptions thatactually theyaremore compact' than shown.

Referring now more lparticularly to Fig. r1,

Vdetails of -the drawings rethere is shown at numeral I a topframe. Theperipheral portions 3 of this frame are formed as inverted U-shapesproviding a guide to eiect placement of the frame upon the upper edgevof a box-like and hollow holding table. It is to be understood thatequivalent downwardly con cave shapes may be substituted for theU-shapes.

Inside of the inverted U-shaped channels 3, the flange I is providedwith an inwardly directed horizontal flange 'I to which are attachedspaced cross channels 9. Thecross channels 9 are also U-shaped,` butwith the open portions of the U-shapes upwardly directed. The bottom,closed portions restupon said flange "L The ends of the members 9 arespaced from the peripheral U-shaped edge 3 asshown'at Il in Fig. 5.

The cross channels 9 and the peripheral frame I areV so related as toprovide a plurality of quadrilateral openings for covers, two of whichare shown for example and indicated at I3 and I5 in Fig. '1. 'I'he thirdopening at the right in Fig. 1 is shown without a cover by way ofexample. These covers, in general, consist of a horizontal sheet I1 inwhich a. suitable opening or openings are cut to receive asuitablyformed flange of a dish or pan or the like. For example, theplate I3 is shown with two round openings I9 for receiving round dishes,and the plate l5 is shown with a single rectangular opening ZI forreceiving a rectangular dish. `Around4 the openings I9 and 2l, as thecase may be,.are beads 2 in which are openings 4, the purpose of whichwill later be described.

The plates, or some of them, may be made ilat and without any adapteropenings but with circulating openings `4, to function merely as closedsupports for dishes and the like. However, the various top plates arethe same size and are interchangeable in the rectangular openings.

Each plate, such as I3 and I5, isprovided about its periphery with adownwardly ilange 23. These flanges at their longitudinal portions resteither in the U-shaped members 9, or upon Y the flange 'I of the frameI, as the case may be. The end portions of the anges 23 are positionedbetween the ends Il of the U-shaped cross mem. bers 9 andthe side of theframe I (see Fig. 5).

'I'he described top Aconstruction results in the ability to vremoveeasily the top plates for cleaning. When replaced they assume asubstantially other. It wm be understood that thefiengtn of the tablemay be made to accommodate fewer or more of thev rectangular tops, suchas I3, I5.

The sides of the table are shown at numeral 25 (Figs. 4 and 5). Theseare turned in at their lower edges, as shown at 21, to support crossmembers 1I. The members 1l in turn support a bottom 59. In connectionwith the bottom 55 is a spaced bottom wall 61 which is held up by meansof flanges I of an er wall structure 55. The inner structure has ailange 5 about its top for resting upon the upper edge of the outer box25. 'I'hus there is formed the inner box 55 having an inner bottom 51,both being spaced from the outer box 25 having a lower bottom 55. 'I'hespaced bottoms 61 and l5 are provided with corrugations Il for strength.The space between parts 25, 65 on the one hand, and 55, 61 on the' otherhand, is iilled with heat insulating material 13.

Passing through the spaced bottoms 61, 59, and through the insulationtherebetween, are open thimbles 14 held in place by beads 12. Associatedcentrally with the thimbles 14 are gas burners 15,`the latter being'fedby means ci branches l from a gas manifold 11. The latter `is supportedin V-notches 15 in the supports 1i.

Above the bottom 61 horizontal-radiator plates 8l are arranged uponsupports 83 in order to absorb the heat from the burners 15 and radiateit upwardly and also to deflect convection currents of heat. Thecombustion burners are preferable to other heaters in the interest lofeconomy. Products of combustion pass upwardly around the plates 8i andoutwardly by leakage through the openings I5 and 2i. The leakage is dueto the relatively loose t that these openings have with the foodcarriers. Convective circulation also takes place through the openingsl.

'I'he space within the inner box 55 is divided by means of dividingplates 5I into as many compartments as there are burner units 15. Thesedivider plates have their upper edges 93 arranged at a short distancefrom the respective U-shaped member 9 to permit a limited communicatibnbetween compartments. At their lower edges the walls 9| are notched asat 94 to clear the upper corrugations I8.

The device is arranged with legs 51, which are longitudinally joined bymeans of a brace 63.

Each branch pipe 8 to each respective burner 15 is under control of thehandle 95 of a valve 95 which may be turned to any one of low, high orolf positions. In high position, the amount of gas burned at a burner isenough to raise the temperature of the respective food carried over therespective compartment A, B or C, and in low position, a pilot burningeffect is had whereby the given temperature may be maintained. The valveused is such that the gas ilow may be adjusted toa predetermined amountat either low or high setting.

-From the above it will be seen that any one (or more) oi' the burners15 may be operated at low or high position of the respective valve 95,and thus that each compartment A, B c r C (de- ,termined by the dividingwalls Si and ends 55D may have its temperature independently controlledand this constitutes one, of the advantages of the invention. Forexample, a long warming table in a cafeteria or the like may have manydiierent foods to be kept at diierent temperatures.

With the old type of steam heated warming Y table, a single mass ofwater was used to heat` all food containers. This had disadvantages, oneof which was that all of the food was `warmed to the same temperature,and secondly that it required more time to bring the relatively largemass of water up to the general temperature desired. Furthermore, themass of water held a large amount of heat which, when radiated intorooms (sometimes refrigerated), unnecessarily overheated them or wererequired vto be absorbed by the refrigeration system. Undesirable hotsteam was also given oil'. With'the 'present invention, any one or moreof the burners 15 may be operated at a high burning rate until the foodVcarried thereover is quickly heated to the proper temperature, afterwhich the respective'valve 95 may be set at the low burning rate whichis such as Yto maintain the respective food temperature at the correctpoint. This involves a heating action only at the respective food incompartment A, B, or C, as the case may be, and therefore greaterheating acceleration may be accomplished with a saving in both time andgas. At the same time, only a smaller amount of material needs to bekept up to temperature under pilot conditions ii! one or more othersections of the table are not being used.

An example of the different heating require- `ments for different foodsis that of mashed po` tatoes as compared with soup. I'he former shouldbe kept at not over F. in order to prevent blackening; while soup mayand should be kept at a temperature of about F. Meats, vegetables andother articles have diierent optimum temperatures which are respectivelyaccommodated by the invention.

Another advantage of the invention is that the radiating plates Il serveto prevent direct conductive or convective impingement oi the heat onthe bottoms of the containers in the openings I! and 2|. That is, theymodulate the heat by receiving it from the respective burners 15 andthen transmitting it to the plate Il by radiation and deiiectedconvection. The convection lines are shown in the drawings. The resultis an even, modulated temperature on the articles being heated,controllable as to the respective sections A, B and C 1 It will be seenthat, when the burners 15 are lighted, combustion occurs at least inpart in the inlet opening and the products of combustion pass upwardlyaround the plates 8l, into the respective compartments A. B or C. as thecase may be. This feature of carrying on the combustion in the 'openingsresults in the advantages of easy lighting. a direct iniiux to the"burner of air for combustion and (in conjunction with the plates Il) theprevention of direct or uneven application of heat to the bottoms offood containers. This is all accomplished without excessive depth of theapparatus. ,That is, the food containers are at the usual desiredelevation while the bottom of the box 25 is quite high. Since the heightoi' a food warmer is limited to the height of adjacent tables and thelike. any reduction in depth of the heating chambers results in increasein desirable storage space beneath. The bottom storage attained byapplicants construction is shown in Fig. 2.

From the above it will be seen that the device forms a box whichconstitutes a dry heater for contained in the above description or shownin the accompanying drawings shall be interpreted as illustrative andnot in a limiting sense.

I claim: 4

1. A food warmer comprising legs, end, side an bottom walls carried bysaid legs forming an outer box; an inner box open at its top, anoutwardly directed flange on the inner box, said ilange resting upon theend and side walls; the inner box being spaced from said side, end andbottom walls; insulation between the container and the side, end andbottom walls; e portions extending through said insulation and bottomsof said boxes; heating means adjacent said ilue portions, and heatdeilecting means above said ilue portions.

2. A food warmer comprising legs, end, side and bottom walls carried bysaid legs forming an outer box; an inner box open at its top, anoutwardly directed ilange on the inner box, said ilange resting throughsaid insulation and bottoms of said boxes; heating means adjacent saidflue portions,

heat deilecting means above said flue portion, and a top comprising aframe having a downwardly 1 open concave cross section positioned overthe upper edge of the outer box, and removable top sections resting uponsaid top..

ing upon the end and side walls; the inner box being spaced from saidside, end and bottom walls; insulation between the container and theside, end and bottom walls; tlue portions extend- 3. Aiood warmercomprising a heat insulated box having individual covers with openingsfor receiving vessels for various foods, means dividing said box intoindividual compartments associated with said individual covers, the boxalso having individual inlet openings through the bottom in connectionwith the respective compartments, heating means associated with saidlastnamed openings,I said heating means comprising gas burners,individual control means for said heating means, and deilector plateslocated above said burners within the respective compartments and spacedabove said openings and adapted to transmit heat by conduction forradiation from the-'tops ofthe plates into the compartments and todetlect convected heat therearound.

MARSH P. DUKE.

